1. Field of the Invention
The invention relates to emulsions containing sunscreens formulated with an improved thickening and stabilization agent, particularly emulsions of the water-in-oil variety.
2. The Related Art
Aqueous cosmetic compositions often require thickeners to achieve an aesthetically pleasing viscosity. Fluids that flow with a watery consistency too rapidly run off the treated skin areas. For a cosmetic to be effective, it often must have substantivity. Thickeners provide this substantivity. Furthermore, low viscosity formulas which may be skin effective nevertheless through their wateriness signal ineffectiveness to the consumer. Products of watery consistency are also aesthetically displeasing to consumers with expectations of rich and creamy products.
Thickening is one but not the only concern when formulating cosmetic emulsions. Phase stability is also of paramount concern. Aqueous and oil phases must be prevented from separating. Gradual loss of viscosity often indicates progressive breakdown of an emulsion.
Certain types of cosmetic ingredients promote emulsion instability. Sunscreen agents are one such class of ingredient. It is difficult to stabilize sunscreen agent containing emulsions, especially water-in-oil emulsions, when seeking systems thickened to an aesthetically pleasing viscosity.
Accordingly, it is an object of the present invention to provide thickened cosmetic sunscreen compositions of sufficiently aesthetically pleasing viscosity.
It is another object of the present invention to provide thickened cosmetic sunscreen compositions stabilized against emulsion breakage and maintainable at substantially constant viscosity.
Still another object of the present invention is to provide a thickened cosmetic sunscreen composition in the form of a water and oil emulsion that exhibits improved aesthetics when applied to the skin.
Yet another object of the present invention is to provide a thickened cosmetic sunscreen composition that maximizes the sun protection factor while minimizing the level of sunscreen agent.
These and other objects of the present invention will more readily become apparent from the description and examples which follow.